Tone frequency signal repeater



July 23, 1946. w, SIMPSON 2,404,754

TONE FREQUENCY SIGNAL REPEATER Filed May 29, 1942 v INVENTOR.

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orramvtr' [wow/v0 Toms 5/ qA A L Patented July 23,1946

UNI -TED PATENT JOFF ICEJ 2,404,754 v a i TONE FREQUENCY SIGNALBEPEATER KWillianr E1: Simpson, .South ozone Park,'iN. 'Y.; assignorxtoRadio Corporation of America, a cor- I poration of- Delaware j AppIi cationMay ZQ,1942;'Serial'Nos44 L991;

This invention relates :to"-tone frequency signal repeaters and more particularly to an arrangeinent which has been found practical in systems of telegraphy. It'is oftentimes desired to'receive telegraphsignalson one channel andtorepeat the same on a different outgoingchannel. "Where the marking and spacing elements of thexsignals are respectively characterized by'on-and off keying of tone yflit has been foun'd that'the tone frequency generator used' at arepea'ting .stationlis apt to hetero'dyne with' the ripple component of the rectified incoming signal. "Such hetero'dyning is-very objectionable in that it does "not-insure the maintenance of signals of uniform amplitude.

Accordingly, it is an object of myinverition to provide a telegraph'repeatercircuit which is electronic-in action and-which permits of sending out a regenerated' tone 'frequencysign'al completely'free'from theefiects-ofa ripple component in the rectified incoming signal. 1

It is another object of my invention to'provide a keying circuit'which would be particularly useful as a repeater; and'to providetherein-=asystem ofelectronic devices "such that no adverse effects Will resultfrom" the use of a rectified incoming signal in keying an output circuitfor the transmission of interrupted tone frequencysignals.

matic form the essential elements of 1 a preferred embodiment of my invention.

"Referring to the drawin ylshow an'i'ncoming tone'signal "circuit whicmincludes the primary t9 Claims. (clans- 66) ator is coupled to i an input circuit of tube 8 "by means of a"'transformer 10. The secondary :of this transformer has'terminals" connected respectively toindividuiil control grids in the tube '8. A mid-tap on the secondary of transformer I0 is coupled across "capacitor II 'to the common cathode of tube 8. This cathode'is grounded. The anodes-of tube Bare connected respectively to the two terminalsof a primary winding on an output transformer T2. The secondary of this transformer is connected to anysuitableout going circuit. In order-"to control'the on and off I keying of the output tube 8, I provideabiasing circuit for its grid which is 'connected to the mid-tap on the secondary of transformer l0 and leads'therefrom to "a tap on apotentiometer l3. This potentiometer is connected between the negative terminalof a "directcurrent source [4 and the anode oftubeS. Sources I 4 and 6 are series-connected.

The operation of my repeater circuit will now be explained.

come ionized; its'anode potentialdrops to a value such thata'cut-ofi bias is appliedthrough potentiometer l3 tothegrids of tube 8. The tone frequency output 'from the generator 9, therefore,

7 has no'efiect uponthe'tubeB during a space winding of-atransformerd. Thesecondaryof this transformer has a" mid-tap which is conminalsof the secondary of the transformer I are connected respectively to the anodes of adouble diode rectifier tube 3. The common cathode of this tube is grounded. A-loadresistor1completes the rectifier tube circuit.

The vacuum tube Thasan-output circuit which includes th space path of a gaseous discharge *tube 5. This-output circuit may be traced completely 'from the cathode of-tube 2 through an "operating potential "source 6, a resistor I, 'the anode of tube 5, "and a :connection between the cathode-of tube5 and theanodeof tube 2.

elemento'f the signal train. 7

Upon-arrival o'f a'markingelement of the incoming tone signal, full'wave rectification'takes place in tube '3. The potential drop resulting in resistor l causes tube*2 tobe completely out oil. 7 The grid in tube {is also rendered negative by virtue of a connection thereto'from'the grid end of resistor"! through "an additional resistor l5. Since no current can 'furthertraverse thespace path of-tube2,the gaseous tube 5 becomes deionized. 'The increase inthe'positi ve potential on the anodedf tub-"i'therfore, is reflected in an increasedvoltage drop through the potentiometer -l3 whichshifts the biasonth'e grids of tube 8 so as to render this tube conductive. The tube will then amplify thetoneifrequency generated by t-he unit yQ-durin-g a markingelemento'f the-'signaltrain.

It will be apparent that the ripple component 'in the rectified-signal as applied to the grid of tube 2 will have noappreciable effect upon the conductive state in the tube 5. In other words, the slight Variation in the'impedance of tube- 5 is negligible in value compared with the changes in value between on and off keying which are attributable to the conductive and non-conductive states in the gaseous tube 5.

While my preferred circuit arrangement has been described in its relation to a repeating system, it will be clear to those skilled in the art that the circuit itself is capable of a variety of different uses under different conditions. In other words, it's use is hotjr'iecessarily;restricted toffifoni and on "keying oftelegraph "signals Other uses may include those which pertain to facsimile systems as well as other systems of communica l tion. The scope of the claims is, therefore, to be understood as though not restricted to the precise details of the exemplary embodimentwhichv ha been shown and describedw I claim: I Y

1'. A gaseous triode discharge, tubein' com-r bination with a device for controlling its periods having input terminals coupled to said source and output terminals coupled to input circuits for both of said tubes, and arranged to bias the vacuum tube to cut-off in the presence of rectified potentials, a direct current operating potential source for said tubes, a keyed tone frequency signal re- 7 peater circuit including a push-pull amplifier, an

j outgoing toiifefjf-requenbyj ource, -,*and j biasing means connected tothe---i nput--'circuit of said amplifier and controlled by alternate conductive qand non-conductive states in said gaseous tube oncausing the output voltage from said outin tone frequency source to be keyed in accord- :ance witlris'aid; incoming signals, "2' 7. ={;'Ih=inethod1of repeating keyed tone signals by' means ="of tw'o discharge tubes the output of ionization, said device comprising a vacuum-dis- 1 3 charge tube having at'least three electrodes of which the anode is connected to thecathode of said gaseous tube, the'vacuum tube-cathode having a circuit connection-to the gaseous tube anode, said circuit connection including a direct current source and a load impedance, an inputcircuit g5 impedance interconnectinga control grid in said vacuum tube with itscathode, an impedance interconnectingthe control grids in the ,two said tub es, and a source of intermittent ,controlpotenr tial which, when applied across said input circuit impedance, causes the vacuum tube tobe blocked,

thereby interrupting -anormaldischarge in said gaseous tube.

2. :The combination according to claim 1 and said sourcev of intermittent control potentials an said input circuit impedance.

3. In. a signal-controlled "circuit, arrangement,

a tube having a gaseous discharge path in series with the discharge path of a vacuum tube, each of said tubes having a cathode, an anode and a control grid, said tubes having a common input circuit impedance across which a rectification component of a tone modulated signal is intermittently impressed, and an output circuit corn 4. The combination accordingto claim and including means; for gdelivering an outgoing ,tone signal; which is keyed on and ofiby differences in the potential drop across said lo ad impedance.

5. The combination'according to claim 3 and including a repeating ci rcuit having a tone frequency generator, anelectronic amplifier subject tojcontrol bysaidgenerator andmeans effective to apply a blocking bias to the input circuit of said amplifier during periods of discharge in said tubes, said means2 comprising a negative biasing 2 source connected in circuit witha potentiometer and connected also to points of different-potential inthe output circuit common to said tubes.

6.;In a signal repeater, a gaseous triode discharge tube the space path of .which is in series with that ofa vacuum tube havingat leasta cathode, an anode and a control grid, a, source of incoming tone frequency signals, rectifying means including rectifying -means, in circuit between,

,circuits -Qf ,Whi Ch are series-connected, one of said tubes being of the vacuum type and the othe'r'tube being gas-filled, which method comprises, rectifying a keyed incoming tone signal,

simultaneously exciting said tubes when said signal is keyed foff utilizing ;a rectified .component of'said ,signalwhen-it is ,keyed f-o'n for biasing said vacuum :tube: "to: cut-0111;; and for thereby extinguishing-said gas filled tube, .gencrating a constant tone frequency, intermittently amplifying saidtone frequency, andcausinglthe periods of amplification :of ,said, tone sfrequency to be defined by corresponding periods ofextinc- -tion of said gas'filled tube. 1

8.- In oombinatiom; a. gaseous discharge ,tube, a vacuum discharge tuba-each of saidtubeshave ing acathode, ananode and acontrol grid,. the cathode in one of saidfltubes beingz directly con nected solely to the anode in the other, of said tubes to form V a series circuit, which includes the dischargepaths. ofthe twosaid tubes, adirect current source; for activating-r said 1, tubes,-

said sourcebeing connected in series with a'load in; an output circuitextending-between the anode and the cathode at the two ends of said series circuit, an input circuit. including ;a-.;resistorinterconnecting the grids iin the two. 1tubes,,and a second resistor interconnecting the, grid andthe cathode of the tube at the negativeend of said'seriesciredit, and common control meansinoluding-a pulsating potential source connected across, sa id second resistor, said means being effective in response to a positive control pulse torender both tubes conductive, and in response to anegative control pulse to blockthe vacuumtube, thus extinguishing the gaseous tube 9. An electronic relay ;c omprising a tube and a gas-filled tube, said tubes having their discharge paths series connectedin a circuitgwhichfis so constituted that the spacepurrent traversing'one tube is always equal inamplitude to the space current traversing the lother tube, adirect 'currentsource for activating, :said tubes, said source being connected in series: with a load in an output circuitextending between the anode and the cathode at thetwo ends-of said series-connected discharge paths, aresistive input circuit a portion of which is individualto one tube and another portion of which is common to the two tubes,control grids in each tube-haw ing connections to saidinput circuit, and means for applying control potentials to said input .circuitin such manner that said tubes are rendered conductive simultaneously, and when thevacuum tube is biased tocut-off then the gas-filled tube becomes extinguished, I

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